Thalassemias (DiPaola L1) Flashcards Preview

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Flashcards in Thalassemias (DiPaola L1) Deck (19):

Which hemoglobin _genes_ are expressed in the first few weeks of life? (0 - 6 wks)
Where is is produced?

Epsilon (beta-like)
Zeta (alpha-like)
--> Gower 1, Gower 2, Portland
yolk salk


Which Hb genes are primarilly expressed as a fetus? (week 6 - birth)

Where are the Hb produced during fetal life?

gamma (beta-like)
Liver--> Spleen--> Bone Marrow


Which Hb genes are primarily expressed after birth?
Where is this Hb produced?

Which Hb is expressed in small amounts after birth?

alpha & beta
Bone Marrow

small amts: gamma


What does the delta (beta-like) Hb gene do?

produced in very small amts as an adult
likely a evolutionary remnant


What are the structural hemoglobinopathies?

What sort of mutations cause these?

Point mutations
HbS Glu6Val
HbC Glu6Lys
HbE Glu26Lys


loss of function? gain? etc?

Novel Function

polymerization of the Hb molecules


What is the histological change that you see in HbC?
What is the clinical presentation?

Crystalization of the hemoglobin in a blood smear.
Can get more infections (give penicillin)

often called HbC trait b/c no other symptoms


According to the formal definition of Thalassemia, what is the problem?

reduced rate of production of one or more chains of Hb.
** abnormal ratio of Hb chain production
defective Hb production & damage to the red blood cells and their precursors


What deletion causes HbH?

3-gene deletion of Hb alpha


What deletion(s) cause alpha thalassemia trait?

alpha-thal 1: deletion of both alphas on one homologue
alpha-thal 2: deletion of one alpha on each homologue


Which alpha hemoglobin gene deletion is clinically insignificant?

if only one of the 4 alpha genes is deleted.


What is Gamma thalassemia?

clinically significant only at birth; no longer a problem at about 6 months of age.
Gamma Hb is a beta-like Hb so eventually beta proper will take over and the gamma deletion is not a problem.


What is delta thalassemia?

By itself is not a problem because delta is a beta-like hb so beta will take over anyway.

if, however you have a delta-beta deletion, now its a problem.


What are normal Hb levels?

all units are gm/dL
Newborns: 17-22
1 week: 15-20
1 month: 11-15
children: 11-13
adult male: 14-18
adult female: 12-16
geriatric male: 12.4 - 14.9
geriatric female: 11.7 - 13.8

So basically if you have in the single digits its Low, upper teens (dep on gender) or higher is High


What is the reticulocyte count and a normal value?

immature red blood cells
blood levels should be low 1-3%

0 is bad and higher levels indicate lots of red blood cell production


What is microcytic and what lab values would indicate this?

low red blood cell counts
MCV (mean corpuscular volume) should be around
76 - 100 fL


What is Cooleys anemia?

beta-thal major
2 severely abnormal or absent beta genes
severe anemia, low MCV count, transfusion dependent
x-ray shows dense marrow expansion in the skull bone changes b/c making marrow in as much bone as you can --> fractures
enlarged spleen & liver
iron overload- body absorbs more b/c trying to make more blood cells


If a pt. is transfusion dependent, what sort of other treatments are indicated?

iron chelation
vitamin C (assists in chelation)
spelenectomy / cholecystectomy
bone marrow transplant


What does the RDW in a CBC tell you and what are normal values?

RDW = red cell distribution width
variability in the size of red blood cells
normal variation values: 11.5 - 14.5%